Load control system having a rotary actuator

ABSTRACT

A load control device for controlling the amount of power delivered from an AC power source to an electrical load comprises a rotary actuator, such as a rotary knob or a rotary wheel. The load control device increases and decreases the amount of power delivered to the electrical load in response to rotations of the rotary knob in first and second directions, respectively. The load control device accelerates the rate of change of the amount of power delivered to the load in response to the angular velocity of the rotary actuator. The load control device generates a ratcheting sound when the rotary actuator is rotated in the first direction at a high-end intensity of the load control device. The load control device is operable to control the electrical load in response to both actuations of the rotary actuator and digital messages received via a communication link.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation application of commonly-assigned U.S.patent application Ser. No. 13/474,220, filed May 17, 2012, now U.S.Pat. No. 8,427,061, issued Apr. 23, 2013, which is a continuationapplication of commonly-assigned U.S. patent application Ser. No.12/955,357, filed Nov. 29, 2010, now U.S. Pat. No. 8,212,486, issuedJul. 3, 2012, which is a continuation application of U.S. patentapplication Ser. No. 12/033,329, filed Feb. 19, 2008, now U.S. Pat. No.7,872,423, issued Jan. 18, 2011, both entitled SMART LOAD CONTROL DEVICEHAVING A ROTARY ACTUATOR, the entire disclosures of which are herebyincorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a load control device for controllingthe amount of power delivered from an alternating-current (AC) powersource to an electrical load, and more particularly, to a smart lightingcontrol device having a rotary intensity adjustment actuator, such as arotary knob or a rotary wheel, for control of the intensity of aconnected lighting load.

2. Description of the Related Art

A conventional wall-mounted load control device is mounted to a standardelectrical wallbox and is coupled between an alternating-current (AC)power source (typically 50 or 60 Hz line voltage AC mains) and anelectrical load. Standard load control devices, such as dimmers andmotor speed controls, use a bidirectional semiconductor switch, such asa triac, or one or more field effect transistors (FETs), to control thecurrent delivered to the load, and thus, the intensity of the lightingload or the speed of the motor. Dimmers have a line terminal (or hotterminal) coupled to the AC power source and a load terminal (e.g., adimmed hot or a switched hot terminal) coupled to the electrical load,such that the semiconductor switch is coupled in series between thesource and the electrical load. Using a phase-control dimming technique,the dimmer renders the semiconductor switch conductive for a portion ofeach line half-cycle and renders the semiconductor switch non-conductivefor the other portion of the line half-cycle to selectively providepower to the load.

A typical dimmer also has a mechanical switch coupled in series with thesemiconductor switch to disconnect the electrical load from the AC powersource to turn the electrical load on and off. An actuator provided atthe user interface of the wall-mounted dimmer allows a user to actuatethe mechanical switch to toggle the load on and off. The dimmer oftencomprises an intensity adjustment actuator to allow the user to adjustthe amount of power being delivered to the load. For example, a priorart rotary dimmer comprises a rotary knob for adjusting a rotarypotentiometer inside the dimmer to adjust the intensity of a connectedlighting load. The rotary knob of the rotary dimmer may also be pressedin to actuate a mechanical switch in the dimmer to turn the lightingload on and off.

Some load control devices, such as “smart” two-wire dimmers, include amicroprocessor or other processing means for providing an advanced setof control features and feedback options to the end user. The advancedfeatures of a smart dimmer may include, for example, a protected orlocked lighting preset, fading, and double-tap to full intensity. Topower the microprocessor, smart two-wire dimmers include power supplies,which draw a small amount of current through the lighting load eachhalf-cycle when the semiconductor switch is non-conductive. The powersupply typically uses this small amount of current to charge a storagecapacitor and develop a direct-current (DC) voltage to power themicroprocessor. An example of a smart dimmer is disclosed in commonlyassigned U.S. Pat. No. 5,248,919, issued on Sep. 28, 1993, entitledLIGHTING CONTROL DEVICE, which is herein incorporated by reference inits entirety.

Smart dimmers have also been included as part of multi-location lightingcontrol systems, such as, for example, a radio-frequency (RF) lightingcontrol system. Such lighting control systems have included main dimmerswired directly to controller lighting loads, and remote control devices(such as keypads or remote dimmers). Each of the main dimmers and remotedimmers of the prior art multi-location lighting control systemstypically comprise, for example, a rocker switch, rather than a rotaryknob or a slider control, for adjustment of the intensity of thelocally-controlled or remotely-controlled lighting loads. Each of themain and remote dimmers may also comprise one or more visual indicators,e.g., light-emitting diodes (LEDs), to provide feedback of the intensityof the controlled lighting load to the user. However, user interfaces ofsuch dimmers are not always easy to understand and use for a novice userof the multi-location lighting control system.

Thus, there is a need for a smart load control device that has a simple,intuitive user interface (for example, including a rotary knob) and isable to be included as part of a multi-location load control system.

SUMMARY OF THE INVENTION

According to the present invention, a system for controlling theintensity of a lighting load comprises a controllably conductive device,a controller, a communication circuit, and a rotary actuator operable torotate in a first direction and a second direction, such as a rotaryknob or a rotary wheel. The controllably conductive device is adapted tobe coupled in series electrical connection between the AC power sourceand the lighting load. The controller is coupled to a control input ofthe controllably conductive device, such that the controller is operableto control the controllably conductive device conductive to adjust theintensity of the lighting load. The communication circuit is operable toreceive digital messages on a communication link. The controller isoperable to adjust the intensity of the lighting load in response to thedigital messages received by the communication circuit. The digitalmessages are transmitted to the communication circuit in response toactuations of the rotary actuator, such that the controller isresponsive to rotations of the rotary actuator to increase the intensityof the lighting load when the rotary actuator is rotated in the firstdirection and to decrease the intensity of the lighting load when therotary actuator is rotated in the second direction. The rotary actuatoris continuously rotatable, such that the position of the rotary actuatoris not representative of the intensity of the lighting load.

The present invention further provides a load control system forcontrolling the intensity of a lighting load powered from an AC powersource. The load control system comprises a load control device adaptedto be coupled in series electrical connection between the AC powersource and the lighting load for controlling the lighting load and arotary actuator operable to rotate in a first direction and a seconddirection. The load control device is operable to receive digitalmessages via a communication link, and to adjust the intensity of thelighting load in response to the received digital messages. The loadcontrol device is operable to increase the intensity of the lightingload when the rotary actuator is rotated in the first direction and todecrease the intensity of the lighting load when the rotary actuator isrotated in the second direction. The rotary actuator is continuouslyrotatable, such that the position of the rotary actuator is notrepresentative of the intensity of the lighting load.

In addition, the present invention provides a control device for a loadcontrol system for controlling the intensity of a lighting load poweredfrom an AC power source. The control device comprises: a rotary actuatoroperable to rotate in a first direction and a second direction; and acontroller responsive to rotations of the rotary actuator, such that theintensity of the lighting load increases when the rotary actuator isrotated in the first direction and decreases when the rotary actuator isrotated in the second direction. The rotary actuator is continuouslyrotatable, such that the position of the rotary actuator is notrepresentative of the intensity of the lighting load.

Other features and advantages of the present invention will becomeapparent from the following description of the invention that refers tothe accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view and FIG. 2 is a front view of a “smart”electronic lamp control module having a rotary knob for control of theamount of power delivered to a lighting load according to the presentinvention;

FIG. 3 is a plot of the rate of change of the amount of power deliveredto the lighting load by the lamp control module of FIG. 1 with respectto the angular speed of the rotary knob;

FIG. 4 is a simplified block diagram of the lamp control module of FIGS.1 and 2;

FIG. 5 is a simplified schematic diagram showing an encoder circuit andan audible sound generator of the lamp control module of FIG. 4;

FIG. 6A is a simplified diagram of a first encoder control signal and asecond encoder control signal when the rotary knob of FIGS. 1 and 2 isturned clockwise;

FIG. 6B is a simplified diagram of the first encoder control signal andthe second encoder control signal when the rotary knob of FIGS. 1 and 2is turned counter-clockwise;

FIG. 7 is a simplified flowchart of a rotary knob press procedureexecuted by a controller of the lamp control module of FIG. 4;

FIG. 8 is a simplified flowchart of a count procedure executed by thecontroller of the lamp control module of FIG. 4;

FIG. 9 is a simplified flowchart of an intensity adjustment procedureexecuted by the controller of the lamp control module of FIG. 4;

FIG. 10 is a simplified flowchart of the intensity acceleration routineexecuted by the controller of the lamp control module of FIG. 4;

FIG. 11 is a simplified flowchart of a count procedure according to asecond embodiment of the present invention;

FIG. 12 is a simplified flowchart of an intensity adjustment procedureaccording to a second embodiment of the present invention;

FIG. 13 is a simplified block diagram of a radio-frequency (RF) lightingcontrol system comprising the lamp control module of FIG. 4;

FIG. 14A is a front view of a wall-mounted dimmer having a rotary knobaccording to the present invention;

FIG. 14B is a right side view of the wall-mounted dimmer of FIG. 14A;

FIG. 15A is a front view of a wall-mounted dimmer having a rotary wheelaccording to the present invention; and

FIG. 15B is a right side view of the wall-mounted dimmer of FIG. 15A.

DETAILED DESCRIPTION OF THE INVENTION

The foregoing summary, as well as the following detailed description ofthe preferred embodiments, is better understood when read in conjunctionwith the appended drawings. For the purposes of illustrating theinvention, there is shown in the drawings an embodiment that ispresently preferred, in which like numerals represent similar partsthroughout the several views of the drawings, it being understood,however, that the invention is not limited to the specific methods andinstrumentalities disclosed.

FIG. 1 is a perspective view and FIG. 2 is a front view of a “smart”electronic lamp control module 100 according to the present invention.The lamp control module 100 has a screw-in base 110, such that the lampcontrol module 100 is adapted to be screwed into a standard Edisonsocket. The lamp control module 100 also includes a socket portion 120(e.g., a standard Edison socket), such that a lighting load 204 (FIG.4), for example, a standard incandescent lamp, may be coupled to andcontrolled by the lamp control module. The lamp control module 100comprises a controllably conductive device 210 (FIG. 4), which iscontained within a housing 130 and provides for control of the amount ofpower delivered to the lighting load 204. When the lamp control module100 is screwed into a standard Edison socket that is powered by an ACpower source 202 (FIG. 4), such as an AC mains voltage (e.g., 120 VAC at60 Hz), and the lighting load 204 is screwed into the socket portion,the controllably conductive device 210 is coupled in series electricalconnection between the AC power source and the lighting load 204 and isrendered conductive and non-conductive to control an intensity level Lof the lighting load.

The lamp control module 100 further comprises a rotary intensityadjustment actuator, e.g., a rotary knob 140, which allows a user toadjust of the intensity level L of the lighting load 204. When the userturns the rotary knob 140 clockwise, the intensity level L of thelighting load 204 is increased until the intensity level reaches amaximum (or high-end) intensity level L_(MAX). As the rotary knob 140 isturned counter-clockwise, the intensity level L of the lighting load 204is decreased until the intensity level reaches a minimum intensity level(e.g., 0%), such that lighting load is turned off. A visual indicator150, e.g., a light emitting diode (LED), is provided below the rotaryknob 140 and is illuminated to provide visual feedback to the user,e.g., to indicate the whether the lighting load 204 is on or off.

The user is operable to push the rotary knob 140 in towards the housing130 of the lamp control module 100 to toggle (i.e., turn on and off) thelighting load 204. Preferably, when the lighting load 204 is turned onin response to a press of the rotary knob 140, the lamp control module100 turns the lighting load on to a preset lighting intensity levelL_(PRESET) (e.g., the intensity level of the lighting load before thelighting load was last turned off). Alternatively, the preset intensitylevel L_(PRESET) could be set to a fixed level, for example, 80%, suchthat the lighting load 204 is controlled to 80% of the maximum intensitylevel L_(MAX) when the rotary knob 140 is pressed to turn on thelighting load.

According to the present invention, the lamp control module 100 controlsthe rate of change dL/dt of the intensity level L of lighting load 204with respect to time in dependence upon the angular velocity ω of therotary knob 140 (i.e., the rate of change dθ/dt of the position of therotary knob). Specifically, the lamp control module 100 is operable toaccelerate the rate of change dL/dt of the intensity level L of lightingload 204 with respect to the angular velocity ω of the rotary knob 140as shown in FIG. 3. For example, if the rotary knob 140 is rotatedclockwise at a first angular velocity ω₁, the lamp control module 100increases the intensity level L of the lighting load 204 at a first rateof change dL₁/dt, where dL₁/dt=α·ω₁. If rotary knob 140 is then turnedmore quickly at a second angular velocity ω₂ greater than the firstangular velocity ω₁, the lamp control module 100 is operable to increasethe intensity level L of the lighting load 204 at a second rate ofchange dL₂/dt, where dL₂/dt=β·ω₂ and β>α. Therefore, the user can turnthe rotary knob 140 slowly to achieve fine resolution in the adjustmentof the intensity level L of the lighting load 204 and can turn therotary knob quickly to achieve a faster response of the intensity levelL of the lighting load 204.

The rotary knob 140 is continuously rotatable, such that the user maycontinue to rotate the rotary knob clockwise after the lighting load 204has reached the high-end intensity L_(MAX). In other words, the rotaryknob 140 does not have maximum and minimum limits, even though theintensity of the lighting load 204 is controlled to maximum and minimumintensities. The position of the rotary knob 140 is not representativeof the intensity level L of the lighting load 204.

The lamp control module 100 is also operable to provide audible feedbackto the user. Specifically, the lamp control module 100 generates a firstaudible sound (e.g., a click at a first frequency f₁) when the lightingload 204 is turned on, and a second audible sound (e.g., a click at asecond frequency f₂) when the lighting load 204 is turned off. Further,the lamp control module 100 is operable to repetitively generate thefirst audible sound (to produce a “ratcheting” sound) when the rotaryknob 140 is rotated clockwise after the lighting load 204 is controlledto the high-end intensity L_(MAX). Accordingly, the user is signaledthat the lighting load 204 is at the high-end intensity L_(MAX) and thatcontinued clockwise rotations of the rotary knob 140 will not affect theintensity level L of the lighting load. When the rotary knob 140 isrotated counter-clockwise until the lighting load 204 is controlled tooff, the lamp control module 100 generates the second audible sound.Alternatively, the lamp control module 100 could generate a ratchetingsound (by repetitively generating the second audible sound) when thelighting load 204 is off and the rotary knob 140 is rotatedcounter-clockwise.

FIG. 4 is a simplified block diagram of the lamp control module 100according to the present invention. As shown, the screw-in base 110 iscoupled to the AC power source 202 and the lighting load 204 is coupledto the socket portion 120. The controllably conductive device 210 iscoupled in series electrical connection between the screw-in base 110and the socket portion 120 for control of the amount of power deliveredto the lighting load 204. The controllably conductive device 210 maycomprise any suitable type of bidirectional semiconductor switch, suchas, for example, a triac, a field-effect transistor (FET) in a rectifierbridge, or two FETs in anti-series connection. A controller 214 iscoupled to a control input of the controllably conductive device 210 viaa drive circuit 212, such that the controller is operable to selectivelyrender the controllably conductive device conductive and non-conductiveto control the intensity level L of the lighting load 204. Thecontroller 214 is preferably implemented as a microcontroller, but maybe any suitable processing device, such as a programmable logic device(PLD), a microprocessor, or an application specific integrated circuit(ASIC). The drive circuit 212 preferably comprises an optocoupler, suchthat the controller 214 is electrically isolated from the AC powersource 202.

A zero-crossing detect circuit 216 determines the zero-crossing pointsof the AC source voltage from the AC power supply 202. A zero-crossingis defined as the time at which the AC supply voltage transitions frompositive to negative polarity, or from negative to positive polarity, atthe beginning of each half-cycle. The zero-crossing information isprovided as an input to the controller 214. The controller 214 generatesthe gate control signals to operate the semiconductor switch 210 to thusprovide voltage from the AC power supply 202 to the lighting load 204 atpredetermined times relative to the zero-crossing points of the ACwaveform.

The controller 214 is operable to control the intensity level L of thelighting load 204 in response the rotary knob 140 and to illuminate thevisual indicator 150 to display feedback to the user of the lamp controlmodule 100. The rotary knob 140 is mechanically coupled to the shaft ofa rotary encoder 310 (FIG. 5) of an encoder circuit 218. In response tothe actuations of the rotary knob 140, the encoder circuit 218 generatesthree control signals, which are provided to the controller 214.Specifically, the encoder circuit 218 generates a toggle control signalV_(TOG), which is representative of the instances when the rotary knob140 is pushed in, i.e., to toggle the lighting load 204 on and off. Theencoder circuit 218 also generates a first encoder control signal V_(E1)and a second encoder control signal V_(E2), which in combination arerepresentative of the angular velocity ω at which the rotary knob 140 isrotated and the direction (i.e., either clockwise or counter-clockwise)in which the rotary knob is rotated.

The lamp control module 100 further comprises an audible sound generator220 coupled to the controller 214. The controller is operable to causethe sound generator to produce the first and second audible sounds inresponse to actuations of the rotary knob 140. A memory 222 is coupledto the controller 214 and is operable to store control information ofthe lamp control module 100, such as the preset intensity levelL_(PRESET) of the lighting load 204. The lamp control module 100comprises a power supply 224, which generates a first direct-current(DC) voltage V_(CC1) (e.g., approximately 2.8 volts) for powering thecontroller 214 and the other low-voltage circuitry of the lamp controlmodule, and a second DC voltage V_(CC2) (e.g., approximately 20 volts)for powering the audible sound generator 220.

The lamp control module 100 may optionally comprise a communicationcircuit, e.g., a radio-frequency (RF) transceiver 226 and an antenna228, such that the controller 214 is operable to transmit and receivedigital messages with other control devices as part of a multi-locationload control system (which will be described in greater detail withreference to FIG. 11). Alternatively, other types of communicationcircuits may be used for transmitting and receiving digital messages onother types of communication links, such as, for example, infrared (IR)communication links, power-line carrier (PLC) communication links, andwired communication links.

FIG. 5 is a simplified schematic diagram showing the encoder circuit 218and the audible sound generator 220 in greater detail. The rotaryencoder 310 of the encoder circuit 218 may comprise, for example, partnumber PEC12-2217F-S0024, manufactured by Bourns, Inc. The three outputsof the rotary encoder 310 are pulled up to the first DC voltage V_(CC1)through resistors R312, R322, R332 (which preferably all haveresistances of 15 kΩ). The outputs of the rotary encoder 310 arefiltered by RC circuits to generate the toggle control signal V_(TOG),the first encoder control signal V_(E1), and the second encoder controlsignal V_(E2). The RC circuits comprise resistors R314, R324, R334(which preferably all have resistances of 15 kΩ), and capacitors C316,C326, C336 (which preferably all have capacitances of 1000 pF).

The rotary encoder 310 includes a single-pole single-throw (SPST)momentary mechanical switch, which is actuated to generate the togglecontrol signal V_(TOG). Accordingly, when the rotary knob 140 is pushedin, the mechanical switch is closed and the toggle control signalV_(TOG) is pulled low towards circuit common (i.e., approximately zerovolts). Otherwise, the toggle control signal V_(TOG) is pulled hightowards the first DC voltage V_(CC1).

The rotary encoder 310 produces two pulse waveforms that are 90°out-of-phase and are filtered by the RC circuits to generate the firstencoder control signals V_(E1) and the second encoder control signalV_(E2). FIG. 6A is a simplified diagram of the first encoder controlsignal V_(E1) and the second encoder control signal V_(E2) when therotary knob 140 is being turned clockwise. FIG. 6B is a simplifieddiagram of the first encoder control signal V_(E1) and the secondencoder control signal V_(E2) when the rotary knob 140 is being turnedcounter-clockwise. The first encoder control signal V_(E1) lags thesecond encoder control signal V_(E2) by 90° when the rotary knob 140 isturned clockwise, while the second encoder control signal V_(E2) lagsthe first encoder control signal V_(E1) by 90° when the rotary knob 140is turned counter-clockwise. Accordingly, the controller 214 is operableto determine whether the second encoder control signal V_(E2) is low(i.e., at approximately circuit common) or high (i.e., at approximatelythe first DC voltage V_(CC1)) at the times of the falling edges of thefirst encoder control signal V_(E1) (i.e., when the first encodercontrol signal V_(E1) transitions from high to low) to thus determinethat the rotary knob 140 is being turned clockwise or counter-clockwise,respectively.

Further, the controller 214 is operable to use the frequency f_(E) ofthe first encoder control signal V_(E1) to determine how fast the rotaryknob 140 is being turned. Specifically, the controller 214 counts thenumber of falling edges of the first encoder control signal V_(E1)during a predetermined time period T (e.g., every 100 msec) anddetermines a corresponding intensity change value ΔINT by which toadjust the intensity level L of the lighting load 204. Preferably, therotary V_(E1) encoder 310 produces a predetermined number N (e.g., 24)of pulses in each of the first and second encoder control signalsV_(E1), V_(E2) during a full rotation (i.e., 360°) of the rotary knob140.

The audible sound generator 220 comprises a piezoelectric buzzer (orspeaker) 340 for generating the first and second audible sounds. Thebuzzer 340 is coupled between the second DC voltage V_(CC2) and circuitcommon through an NPN bipolar junction transistor Q342. A resistor R344is coupled across the buzzer 340 and preferably has a resistance of 1kΩ. The controller 214 is coupled to the base of the transistor Q342 viaa circuit comprising two resistors R346, R348 (preferably havingresistances of 3.3 kΩ and 15 kΩ, respectively) and a capacitor C350(preferably having a capacitance of 0.01 μF).

The controller 214 is operable to control the transistor Q342 to beconductive and non-conductive in predetermined fashions to cause thebuzzer 340 to generate the first and second audible sounds. For thefirst audible sound, the controller 214 generates three pulses ofvoltage across the buzzer 340 at a first frequency f₁ (e.g., 1500 Hz) ata first duty cycle (e.g., 12%). Specifically, the transistor Q342 isrepetitively rendered conductive for 80 μsec and then non-conductive for587 μsec to generate the three pulses. For the second audible sound, thecontroller 214 generates three pulses of voltage across the buzzer 340at a second frequency f₂ (e.g., 4319 Hz) at a second duty cycle (e.g.,37%), such that the transistor Q342 is repetitively rendered conductivefor 80 μsec and then non-conductive for 145 μsec to generate the threepulses.

FIG. 7 is a simplified flowchart of a rotary knob press procedure 400,which is executed by the controller 214 in response to a falling edge ofthe toggle control signal V_(TOG) at step 410. If the lighting load 204is presently off at step 412, the controller 214 turns the lighting loadon to the preset intensity level L_(PRESET) stored in the memory 222 atstep 414 and generates the first audible sound at step 416, before thepress procedure 400 exits. Otherwise, if the lighting load 204 ispresently on at step 412, the controller 214 stores the presentintensity level L as the preset intensity level L_(PRESET) in the memory222 at step 418, and turns the lighting load 204 off at step 420. Thecontroller 214 then generates the second audible sound at step 422, andthe press procedure 400 exits.

FIG. 8 is a simplified flowchart of a count procedure 500, which isexecuted by the controller 214 in response to a falling edge of thefirst encoder control signal V_(E1) at step 510. The controller 214 usesa counter to keep track of the number of falling edges (i.e., the numberof pulses) of the first encoder control signal V_(E1) that have occurredduring the predetermined timer period T to determine how fast the rotaryknob 140 is being turned. If the second encoder control signal V_(E2) islow at step 512 (i.e., the rotary knob 140 is being turned clockwise),the controller 214 increments the counter by one at step 514 and thecount procedure 500 exits. Otherwise, if the rotary knob 140 is beingturned counter-clockwise at step 512, the controller 214 decrements thecounter by one at step 516, before the count procedure 500 exits.

FIG. 9 is a simplified flowchart of an intensity adjustment procedure600 executed periodically by the controller 214 (e.g., at the beginningof each predetermined time period T, i.e., every 100 msec). If thecounter has not changed in value at step 610 since the last time thatthe intensity adjustment procedure 600 was executed, the intensityadjustment procedure 600 simply exits. However, if the counter haschanged in value at step 610 since the last execution of the intensityadjustment procedure 600, the controller 214 analyzes the number offalling edges of the first encoder control signal V_(E1) that occurredin the last time period T (i.e., in the last 100 msec). Specifically, atstep 612, the controller 214 reads the value of the counter and storesthis value in a variable ΔCNT for use during the intensity adjustmentprocedure 600. Since the value of the counter is recorded at thebeginning of each predetermined time period T, the counter value ΔCNT isrepresentative of the angular velocity ω of the rotary knob 140, i.e.,ω=[(ΔCNT/N)·360°]/T.

The controller 214 executes an intensity acceleration routine 700 todetermine the intensity change value ΔINT in response to the countervalue ΔCNT. During the intensity acceleration routine 700, thecontroller 214 applies an appropriate acceleration to the intensitychange value ΔINT in response to how quickly the rotary knob 140 isbeing turned. After the intensity acceleration routine 700 is executed,the intensity change value ΔINT is added to or subtracted from a targetintensity level L_(TARGET), which is used to determine the actual amountof power delivered to the lighting load 204. The target intensityL_(TARGET) preferably comprises an integer between 0 (when the lightingload 204 is off) and 255 (when the lighting load is at the high-endintensity L_(MAX)). Since the lighting load 204 is controlled to thetarget intensity L_(TARGET) once each predetermined time period T andthe target intensity L_(TARGET) is determined from the counter valueΔCNT, the rate of change dL/dt of the intensity level L of the lightingload is dependent upon the angular velocity ω of the rotary knob 140.

FIG. 10 is a simplified flowchart of the intensity acceleration routine700. If the absolute value of the counter value ΔCNT is less than orequal to two (2) at step 710, the intensity change value ΔINT is setequal to a constant η times the absolute value of the counter value ΔCNTat step 712. Preferably, the constant η equal eight. After the intensitychange value ΔINT is set at step 712, the procedure 700 exits. If theabsolute value of the counter value ΔCNT is greater than two (2) at step710, but is less than or equal to a maximum counter change value ΔMAX,e.g., six (6), at step 714, the controller 214 applies the accelerationto the desired intensity change value ΔINT. Specifically, at step 716,the intensity change value ΔINT is computed as follows:ΔINT=η·2^((|ΔCNT|−)1) ,and the intensity acceleration routine 700 exits. In other words, theintensity change value ΔINT is set equal to the constant η times two tothe power of the quantity (|ΔCNT|−1) at step 716. If the absolute valueof the counter value ΔCNT is greater than the maximum counter changevalue ΔMAX at step 714, the intensity change value ΔINT is limited to:ΔINT=η·2^((|ΔMAX|−)1),at step 718, before the intensity acceleration routine 700 exits. Inother words, the intensity change value ΔINT is set equal to theconstant η times two to the power of the quantity (|ΔMAX|−1) at step718.

Alternatively, during the intensity acceleration routine 700, thecontroller 214 could use a lookup table to determine the intensitychange value ΔINT. For example, if the constant η equals eight (8), thecontroller 214 could use the absolute value of the counter value ΔCNT asthe index in the following table to determine the intensity change valueΔINT.

|ΔCNT| ΔINT 1 8 2 16 3 32 4 64 5 128 ≧6 255

Referring back to FIG. 9, after executing the intensity accelerationroutine 700, the intensity change value ΔINT is applied to the targetintensity L_(TARGET). Specifically, if the counter value ΔCNT is greaterthan zero (i.e., positive) at step 614, the target intensity L_(TARGET)is set equal to the target intensity L_(TARGET) plus the intensitychange value ΔINT at step 616. Otherwise, if the counter value ΔCNT isnegative at step 614, the target intensity L_(TARGET) is set equal tothe target intensity L_(TARGET) minus the intensity change value ΔINT atstep 618.

If the target intensity L_(TARGET) is greater than zero at step 620 andless than the maximum intensity level L_(MAX) (i.e., 255) at step 622, adetermination is made at step 624 as to whether the lighting load 204was just turned on. If not, the controller 214 simply subtracts thecounter value ΔCNT being used during the present execution of theintensity adjustment procedure 600 from the counter at step 626, beforethe intensity adjustment procedure 600 exits. Accordingly, the next timethat the intensity adjustment procedure 600 is executed, the controller214 will consider the change in the value of the counter during thesubsequent time period T, i.e., during the subsequent 100 msec. If thelighting load 204 was just turned on at step 624, the controller 214generates the first audible sound at step 628 and subtracts the countervalue ΔCNT from the counter at step 626, before the intensity adjustmentprocedure 600 exits.

If the target intensity level L_(TARGET) is less than or equal to zeroat step 620 (i.e., the lighting load 204 is off), the controller 214limits the target intensity L_(TARGET) to zero at step 630. If thelighting load 204 was not just turned off (during the present executionof the intensity adjustment procedure 600) at step 632, the controller214 subtracts the counter value ΔCNT from the counter at step 626 andthe procedure exits. However, if the lighting load 204 was just turnedoff at step 632, the controller 214 generates the second audible soundat step 634 and stores a minimum non-zero intensity level L_(MIN), e.g.,one (1), as the preset intensity L_(PRESET) in the memory 222 at step636, before the counter value ΔCNT is subtracted from the counter atstep 626 and the procedure 600 exits.

If the target intensity level L_(TARGET) is greater than or equal to themaximum intensity level L_(MAX) at step 622 (i.e., the lamp controlmodule 100 is at the high-end intensity), the target intensityL_(TARGET) is limited to the maximum intensity level L_(MAX) at step638. The controller 214 then generates the first audible sound at step628, before the counter value ΔCNT is subtracted from the counter atstep 626 and the procedure 600 exits. Accordingly, when rotary knob 140is being turned (i.e., the counter is changing) and the lamp controlmodule 100 is at the high-end intensity at step 622, the controller 214generates the first audible sound each time that the intensityadjustment procedure 600 is executed, i.e., once every 100 msec, to thusgenerate the ratcheting sound at a constant frequency f_(CON).

FIGS. 11 and 12 are simplified flowcharts of a count procedure 500′ andan intensity adjustment procedure 600′, respectively, according to asecond embodiment of the present invention. The count procedure 500′ andthe intensity adjustment procedure 600′ are very similar to the countprocedure 500 and the intensity adjustment procedure 600 of the firstembodiment. However, the controller 214 does not generate the firstaudible sound each time that the intensity adjustment procedure 600′ isexecuted when the lamp control module 100 is at the high-end intensityat step 622′ and the rotary knob 140 is being turned. Instead, when theload control module 100 is at the high-end intensity at step 622′, thecontroller 214 only generates the first audible sound during theintensity adjustment procedure 600′ (at step 628′) if the lighting load204 was just turned on step 624′. The controller 214 creates theratcheting sound by generating the first audible sound each time thatthe count procedure 500′ is executed (at step 520′) when the rotary knob140 is being turned and the lamp control module 100 is at the high-endintensity at step 518′. Since the count procedure 500′ is executed inresponse to the falling edges of the first encoder control signalV_(E1), the first audible sound is generated repetitively at step 520′at a variable frequency f_(VAR) in response to angular speed of therotary knob 140. Accordingly, the faster than the rotary knob 140 isrotated clockwise at the high-end intensity, the more often the firstaudible sound will be generated at step 520′. In other words, as theangular speed ω of the rotary knob 140 increases at the high-endintensity, the variable frequency f_(VAR) of the ratcheting sound alsoincreases, and vice versa.

FIG. 13 is a simplified block diagram of a radio-frequency (RF) lightingcontrol system 800 comprising the lamp control module 100. The RFlighting control system 100 comprises a wall-mounted dimmer 810 and awall-mounted keypad 820. The lamp control module 100, the dimmer 810,and the keypad 820 are operable to communicate with each other bytransmitting and receiving digital messages across an RF communicationlink via RF signals 808.

FIG. 14A is a front view and FIG. 14B is a right side view of thewall-mounted dimmer 810. The dimmer 810 is operable to control theintensity of a connected lighting load 806, and comprises a rotaryintensity adjustment actuator, e.g., a rotary knob 812, for adjustingthe intensity of the lighting load. The rotary knob 812 may also bepressed in towards the dimmer 810 in order to toggle the lighting load806 on and off as with the lamp control module 100. The dimmer 810further comprises a plurality of visual indicators 814 (e.g., LEDs) fordisplaying the intensity of the lighting load 806.

The keypad 820 comprises a plurality of preset buttons 822 (e.g., fivebuttons), which may be programmed, for example, to recall lightingpresets or toggle one or more lighting loads 204, 806 on and off. Thekeypad 820 also comprises a plurality of visual indicators 824 (e.g.,LEDs) for displaying feedback of, for example, which preset is selectedor which lighting loads 204, 806 are energized. The RF lighting controlsystem 800 also may comprise a signal repeater 830, which re-transmitsany received digital messages to ensure that all of the control devicesof the RF lighting control system 800 receive all of the RF signals 808.The signal repeater 830 is adapted to be coupled to the AC mains voltagevia a power supply 832 plugged into an electrical outlet 834. The lampcontrol module 100 is screwed into a socket 842 of a table lamp 840. Thetable lamp 840 comprises an electrical plug 844 that is plugged into anelectrical outlet 846 for powering the lighting load 204. An example ofan RF lighting control system is described in greater detail incommonly-assigned co-pending U.S. patent application Ser. No.12/033,223, filed Feb. 19, 2008 , entitled COMMUNICATION PROTOCOL FOR ARADIO-FREQUENCY LOAD CONTROL SYSTEM, the entire disclosure of which ishereby incorporated by reference.

The lamp control module 100 and the wall-mounted dimmer 810 are operableto adjust the intensity level of the respective lighting loads 204, 806in response to both the digital messages transmitted via the RFcommunication link and the actuations and rotations of the respectiverotary knobs 140, 812. Since the rotary knobs 140, 812 have continuousrotations (i.e., no limits), turning each rotary knob in eitherdirection adjusts the intensity level L of the respective lighting load204, 806 from the present intensity level to the desired intensitylevel. Therefore, there are no discontinuities in the fading of theintensity levels L of the lighting loads 204, 806. The position of eachrotary knob 140, 812 is not representative of the intensity level L ofthe respective lighting load 204, 806.

The lamp control module 100 and the dimmer 810 are also operable tocontrol remotely-located electrical loads. For example, the RF lightingcontrol system 800 could be configured such that the dimmer 810transmits digital messages to the load control module 100 in response torotations of the rotary knob 812 and the load control module 100controls the intensity level of the connected lighting load 204 inresponse to the digital message, i.e., in response to the rotations ofthe rotary knob 812 of the dimmer 810.

FIG. 15A is a front view and FIG. 15B is a right side view of awall-mounted dimmer 850 having a rotary wheel 852 rather than the rotaryknob 812. The user is operable to rotate the rotary wheel 852 upwards toincrease the intensity of a connected lighting load and to rotate therotary wheel downwards to decrease the intensity of the connectedlighting load. The dimmer 850 is operable to provide acceleration of theintensity level of the lighting load 806 if the rotary wheel 852 isrotated quickly. Further, the dimmer 850 is operable to generate theratcheting sound if the rotary wheel 852 is rotated upwards when theconnected lighting load is at the high-end intensity. The dimmer 850also comprises a plurality of visual indicators 854 (e.g., LEDs) fordisplaying the intensity of the connected lighting load. Alternatively,the lamp control module 100 could also include a rotary wheel (notshown) rather than the rotary knob 140.

Although the present invention has been described in relation toparticular embodiments thereof, many other variations and modificationsand other uses will be apparent to those skilled in the art. It ispreferred, therefore, that the present invention be limited not by thespecific disclosure herein, but only by the appended claims.

What is claimed is:
 1. A system for controlling the intensity of alighting load powered from an AC power source, the load control devicecomprising: a controllably conductive device adapted to be coupled inseries electrical connection between the AC power source and thelighting load; a controller coupled to a control input of thecontrollably conductive device, the controller operable to control thecontrollably conductive device to adjust the intensity of the lightingload; a communication circuit operable to receive digital messages on acommunication link, the controller coupled to the communication circuit,such that the controller is operable to adjust the intensity of thelighting load in response to the received digital messages; and a rotaryactuator operable to rotate in a first direction and a second direction,the digital messages transmitted to the communication circuit inresponse to actuations of the rotary actuator, such that the controlleris responsive to rotations of the rotary actuator to increase theintensity of the lighting load when the rotary actuator is rotated inthe first direction and to decrease the intensity of the lighting loadwhen the rotary actuator is rotated in the second direction; wherein therotary actuator is continuously rotatable, such that the position of therotary actuator is not representative of the intensity of the lightingload.
 2. The system of claim 1, further comprising: a rotary encoderhaving a shaft coupled to the rotary actuator and operable to generateone or more control signals in response to the rotations of the rotaryactuator.
 3. The system of claim 2, wherein the rotary encoder iscoupled to the controller, such that the controller is operable todetermine the direction of rotation of the rotary actuator in responseto the one or more control signals and to control the intensity of thelighting load in response to the one or more control signals.
 4. Thesystem of claim 3, wherein the rotary encoder includes a switch forgenerating a toggle control signal, the controller operable to receivethe toggle control signal for turning the lighting load on and off whenthe rotary actuator is pushed in towards the load control device.
 5. Thesystem of claim 1, wherein the communication circuit comprises an RFtransceiver operable to receive digital messages on an RF communicationlink.
 6. The system of claim 1, further comprising: a housing forcontaining the controllably conductive device; and a screw-in baseconnected to the housing and adapted to be screwed into a standardEdison socket to allow for connection to the AC power source.
 7. Thesystem of claim 1, wherein the rotary actuator comprises a rotary knobadapted to be rotated such that the first direction is clockwise and thesecond direction is counter-clockwise.
 8. The system of claim 1, whereinthe rotary actuator comprises a rotary wheel.
 9. The system of claim 1,wherein the controller is operable to avoid discontinuities in theadjustment of the intensity of the lighting load in response toactuations of the rotary actuator, the rotary actuator operable tocontinue to rotate when the intensity of the lighting load is at themaximum intensity.
 10. A load control system for controlling theintensity of a lighting load powered from an AC power source, the loadcontrol system comprising: a load control device adapted to be coupledin series electrical connection between the AC power source and thelighting load for controlling the lighting load, the load control deviceoperable to receive digital messages via a communication link, and toadjust the intensity of the lighting load in response to the receiveddigital messages; and a rotary actuator operable to rotate in a firstdirection and a second direction, the load control device operable toincrease the intensity of the lighting load when the rotary actuator isrotated in the first direction and to decrease the intensity of thelighting load when the rotary actuator is rotated in the seconddirection; wherein the rotary actuator is continuously rotatable, suchthat the position of the rotary actuator is not representative of theintensity of the lighting load.
 11. The load control system of claim 10,wherein the load control device is operable to control the amount ofpower delivered to the lighting load in order to adjust an intensity ofthe lighting load between a minimum intensity and a maximum intensity,the load control device operable to avoid discontinuities in theadjustment of the intensity of the lighting load in response toactuations of the rotary actuator.
 12. The load control system of claim11, wherein, after the intensity of the lighting load is controlled tothe maximum intensity, the load control device is operable to maintainthe intensity of the lighting load at the maximum intensity if therotary actuator is further rotated in the first direction.
 13. The loadcontrol system of claim 10, wherein the communication link comprises anRF communication link.
 14. The load control system of claim 13, furthercomprising: a keypad comprising at least one button, and operable towirelessly transmit digital messages on the RF communication link inresponse to actuations of the button.
 15. The load control system ofclaim 10, wherein the digital messages are transmitted to the loadcontrol device in response to actuations of the rotary actuator.
 16. Theload control system of claim 10, wherein the load control devicecomprises a screw-in base adapted to be screwed into a standard Edisonsocket to allow for connection to the AC power source.
 17. The loadcontrol system of claim 10, further comprising: a rotary encoder havinga shaft coupled to the rotary actuator and operable to generate one ormore control signals in response to the rotations of the rotaryactuator.
 18. The load control system of claim 10, wherein the rotaryactuator comprises a rotary knob adapted to be rotated such that thefirst direction is clockwise and the second direction iscounter-clockwise.
 19. The load control system of claim 10, wherein therotary actuator comprises a rotary wheel.
 20. A control device for aload control system for controlling the intensity of a lighting loadpowered from an AC power source, the control device comprising: a rotaryactuator operable to rotate in a first direction and a second direction;and a controller responsive to rotations of the rotary actuator, suchthat the intensity of the lighting load increases when the rotaryactuator is rotated in the first direction and decreases when the rotaryactuator is rotated in the second direction; wherein the rotary actuatoris continuously rotatable, such that the position of the rotary actuatoris not representative of the intensity of the lighting load.
 21. Thecontrol device of claim 20, further comprising: a rotary encoder havinga shaft coupled to the rotary actuator and operable to generate one ormore control signals in response to the rotations of the rotaryactuator, the controller operable to control the intensity of thelighting load in response to the one or more control signals.
 22. Thecontrol device of claim 21, wherein the rotary encoder is coupled to thecontroller, such that the controller is operable to determine thedirection of rotation of the rotary actuator in response to the one ormore control signals and to control the intensity of the lighting loadin response to the one or more control signals.
 23. The control deviceof claim 22, wherein the rotary encoder includes a switch for generatinga toggle control signal, the controller operable to receive the togglecontrol signal for turning the lighting load on and off when the rotaryactuator is pushed in towards the load control device.
 24. The controldevice of claim 20, further comprising: a controllably conductive deviceadapted to be coupled in series electrical connection between the ACpower source and the lighting load; wherein the controller is coupled toa control input of the controllably conductive device for controllingthe controllably conductive device to adjust the intensity of thelighting load.
 25. The control device of claim 24, further comprising: acommunication circuit operable to receive digital messages; wherein thecontroller is coupled to the communication circuit, such that thecontroller is operable to adjust the intensity of the lighting load inresponse to the received digital messages.
 26. The control device ofclaim 20, further comprising: a communication circuit operable totransmit digital messages in response to rotations of the rotaryactuator.